1. Field of the Invention
This invention relates to a method for producing site-specific recombination of DNA in eukaryotic cells.
2. Background of the Invention
Many eukaryotic cells, including yeast, are promising hosts for commercial applications of genetic engineering. A method for producing site-specific recombination of DNA in eukaryotic cells would enhance the commercial potential of these cells as hosts for genetically engineered products. In addition, methods for producing site-specific recombination of DNA in eukayotic cells, such as mammalian cells, are of interest to the medical field.
Abremski et al., Cell, 32: 1301--1311 (1983) disclose a site-specific recombination system of bacteriophage P1. The system consists of a recombination site designated loxP and a recombinase designated Cre. The authors show that recombination between loxP sites on supercoiled, nicked-circle or linear DNA occurs in the presence of Cre.
Brent et al., Nature, 312: 612-615 (1984) disclose that a bacterial repressor protein or a yeast transcriptional terminator can block upstream activation of a yeast gene. Disclosed experiments are said to provide genetic evidence that a bacterial repressor protein manufactured in the yeast cytoplasm can enter the yeast nucleus, recognize its operator and repress gene transcription from a yeast promoter.
Barnes et al., Proc. Natl. Acad. Sci. 82: 1354-1358 (1985) disclose that the bacterial restriction enzyme Eco RI is able to enter and function within the nucleus of Saccharomyces cerivisiae when the procaryotic protein is synthesized in vivo.
Backman et al., Bio/Technology (December, 1984) disclose a site-specific recombination system of the bacteriophage lambda. The system catalyzes recombination between two different sites in DNA, designated attP and attB, to yield two other different sites, designated attR and attL, or vice versa. Recombination occurs only in the presence of certain E. coli proteins and the Int protein of bacteriophage lambda and can be used to regulate gene expression of E. coli Langeveld et al., Mol. Gen. Genet., 199:396-400 (1985) disclose expression of an E. coli phr gene in yeast Saccharomyces cerevisiae.